Great, although wasnt as great as the previous games.
But still, MUCH BETTER than Colonial Marines.
In this game, you can also play as the Aliens and the Predators other than the Marines. The Marines campaign was the scariest of the bunch, since you're alone armed with your Pulse Rifle and looking for Aliens in the dark with your Flashlight. The Predator campaign is really awesome, because you get to use the predator's weapons (Wrist blade, Plasma cutter, dll). But, the Aliens campaign is lacking compared to others. It just feels lackluster.
Overall, with the price of $24.90, this game is MUST BUY, especially if you're a fan of the Aliens movies and comics.